The present invention relates to a transfer feeder for taking hold of articles and transferring them back and forth, left and right or up and down and, more particularly, to a three-dimensional transfer feeder of mechanical type which is useful to utilize for taking the parts to be pressed into or out of a press machine.
Conventionally, a transfer feeder of this type has been arranged such that a pair of feed bars extending horizontally would hold work-pieces and transfer them in the directions of two or three dimensions and, as a driving mechanism for such feed bars, a combination of cams, hydraulic cylinders and gear mechanisms etc. is employed. Further, driving mechanisms for moving the feed bars up and down (a lift system), left and right (a clamp system), and back and forth (an advance system) are driven by at least more than two driving sources, and timing of those respective motions for the feed bars are determined by means of limit switches or the like.
The foregoing conventional mechanical transfer feeder necessitates a plurality of driving sources and, therefore, this feeder is complicated in structure and becomes unsuitable for high speed operation. In other words, in case of the conventional structure, for example, levers, links or gears and so on are complicatedly incorporated between driving cams and the feed bars, that is final operation members, so as to provide a large number of jointed portions therebetween. These jointed portions will come to play during the reciprocal movement of respective operation shafts connected to the feed bars, so that this play motions preclude that mechanism from smoothly driving. Due to many interposed members in mechanisms, acceleration generated upon running of the mechanisms leads each member to deform so that errors may occur in the feed bar actions with respect to the operational displacements of the cams. For these reasons, vibration will be happened on the feed bars and in the operating system. Furthermore the feeder must cover the working functions having three dimensions, and this causes a problem to the feeder, resulting in heavy weight for each of the operating systems (the clamp, lift, advance systems).